Resideo TH105PLUS/U Line Volt 5-2 Programmable Thermostat with TRIAC for Electric Heat

Item #: HONE-TH105PLUS/U
Mfr. part #: TH105PLUS/U
UPC: 775264105005

Key specifications

ColorWhite
MountingVertical
Supply Voltage120/240 Vac
Frequency60 Hz
Ambient Temperatur32 F to 122 F

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$83.10

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Shipping details

Shipping weight: 1.0 lb
Box size: 6.2 × 5.4 × 2 in

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Brand	Resideo
Manufacturer part #	TH105PLUS/U
Supply Voltage	120/240 Vac
Frequency	60 Hz
Electrical Connections	6 in. (150 mm) tinned copper lead wires
Electrical Ratings	Minimum Load: 0.83A (resistive only) 200W @240 Vac, 100W @ 120 Vac; Maximum Load: 14.6 A (resistive only), 3500W @ 240 Vac, 1750 W @ 120 Vac
Ambient Temperature	32 F to 122 F
Mounting	Vertical
Application	Electric Heating; Baseboard heater; Convector or Fan-forced Heater
Dimensions	4.9 in. X 5 in. x 1.4 in.
UL	Approved
CSA	Approved; Compliant to CAN/CSA-C828-06
Shipping and Storage Temperature Range (F)	-4 F to 120 F
Power Method	Hardwired
Color	White
Sensor Element	Thermistor
Accuracy (F)	0.27 F (0.9 F for fan-forced heaters)
Differential Temperature (F)	0.27 F
Switching Action	SPST
Switch Type	Triac
Programmability	5-2 Day Program
Setting Temperature Range (F)	41 F to 86 F
UPC	775264105005

TH105PLUS has been discontinued by the manufacturer (2018-11). No direct replacement has been published by the manufacturer. Contact us for help choosing an alternative.

The TH105PLUS is a line-voltage thermostat from Resideo (Honeywell Home) for electric resistance heat — baseboard, convectors, radiant ceiling or panel heaters.

Line voltage is the distinction that matters here. A low-voltage thermostat switches a 24 V control circuit and lets a furnace or boiler do the work; a line-voltage thermostat carries the full heater current itself. They are not interchangeable, and a low-voltage stat wired to a baseboard circuit fails immediately.

Switching is by TRIAC rather than by mechanical contacts. A TRIAC has nothing to burn or weld, so it holds a much tighter temperature band than a bimetal stat and it does not develop the contact chatter that makes an old baseboard thermostat click all evening.

The 5-2 schedule lets the heat drop back when the room is empty and recover before it is used again. On electric resistance heat, where every watt is billed at full price, setback is the single largest saving available — there is no efficiency to improve, only run time to remove.

Match the voltage and the pole configuration to the heater circuit, and check the amperage of the heater against the rating of the thermostat. A thermostat sized below the load is the most common cause of a line-voltage stat failing in its first season.